Next check the ohms. If using the Lavatube use the built in ohms checker and make sure the ohms are reading what they should for the atomizer you are using. If you do not have the Lavatube, then if you have a multimeter you can use that to check the ohms of the atomizer. You can do this by touching one lead to the threads and the other lead of the meter to the bottom plate of the threaded connection. If you get a reading that is not near what the factory ohm reads should be then the heating coil in the atomizer is broke and you will need a new atomizer. If it reads correctly then continue reading.

Is the atomizer making connection to the battery?

The center connection plate of the battery and atomizer "float" and can get moved. If the plate in the battery connection does not make contact with the battery then will not complete the connection and not supply power to the atomizer. To Fix this please check out the Adjusting your Plate article.